Bearing module

ABSTRACT

In a hub unit of a bearing module, an outer end face of an attachment flange of an outer ring in a vehicle lateral direction is located further outward in the vehicle lateral direction than a point of a load applied to the outer ring from rolling elements located on an outer side in the vehicle lateral direction. A fitting surface for determining a radial position of the outer ring with respect to an inner periphery defining a supporting hole is formed on an outer periphery of an insertion portion. An inner edge of the fitting surface in the vehicle lateral direction is located further inward in the vehicle lateral direction than a point of a load applied to the outer ring from the rolling elements located on an inner side in the vehicle lateral direction.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2014-000535 filed on Jan. 6, 2014 including the specification, drawings and abstract, is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a bearing module for rotatably attaching a wheel to a vehicle body of a vehicle such as an automobile.

2. Description of Related Art

As a device for rotatably attaching a wheel to a vehicle body of a vehicle such as an automobile, for example, there has been known a bearing module that includes a knuckle forming a part of a suspension, and a hub unit attached to the knuckle and having a wheel fixed thereto (for example, see Japanese Patent Application Publication No. 2011-94728 (JP 2011-94728 A)). FIG. 6 is a cross-sectional view showing an example of a conventional bearing module. FIG. 7 is a partial enlarged view of FIG. 6. As shown in FIGS. 6 and 7, a bearing module 31 includes a knuckle 32 having a hub unit supporting hole 32 a, and a hub unit 34. A wheel 33 and a brake rotor 44 that are wheel-side components are attached to the hub unit 34. In FIGS. 6 and 7, a side on which the wheel is attached (the right side in FIGS. 6 and 7) is an outer side in a vehicle lateral direction, and a center side of the vehicle body (the left side in FIGS. 6 and 7) is an inner side in the vehicle lateral direction. In addition, in FIGS. 6 and 7, an upper side of each figure is an upper side of the bearing module 31, and a lower side of each figure is a lower side of the bearing module 31.

The hub unit 34 has an outer ring 35, an inner shaft 37, outer balls 38 located on the outer side in the vehicle lateral direction, and inner balls 39 located on the inner side in the vehicle lateral direction. The outer ring 35 has an attachment flange 35 a. The inner shaft 37 has a flange portion 37 a. The outer balls 38 located on the outer side in the vehicle lateral direction and the inner balls 39 located on the inner side in the vehicle lateral direction are disposed between the outer ring 35 and the inner shaft 37. A part of the outer ring 35, which is located on the inner side in the vehicle lateral direction with respect to the attachment flange 35 a, serves as an insertion portion 35 b, and the insertion portion 35 b is inserted and fitted into the supporting hole 32 a of the knuckle 32. The attachment flange 35 a is attached to the knuckle 32 by bolts 36. The wheel 33 and the brake rotor 44 are attached to the flange portion 37 a.

In the conventional bearing module 31 as shown in FIGS. 6 and 7, the attachment flange 35 a is formed at a position inward in the vehicle lateral direction in the outer ring 35. In this configuration, providing the attachment flange 35 a can ensure adequate rigidity of an inner part of the outer ring 35 in the vehicle lateral direction. Even if a large load F4 is applied from the inner balls 39 to an upper portion 35 c of the inner part of the outer ring 35 in the vehicle lateral direction during cornering of the vehicle, etc., the upper portion 35 c is therefore less likely to deform radially outward. The load F4 is applied to the upper portion 35 c through a point P4 of the load applied from the inner balls 39 to the outer ring 35. The upper portion 35 c means a portion of the inner part of the outer ring 35 in the vehicle lateral direction, which is located on the upper side with respect to a central axis of the outer ring 35.

In the conventional configuration as shown in FIGS. 6 and 7, an outer end face 35a1 of the attachment flange 35 a in the vehicle lateral direction is located further inward in the vehicle lateral direction than a point P3 of the load applied from the outer balls 38 to the outer ring 35. Accordingly, an outer part of the outer ring 35 in the vehicle lateral direction has low rigidity. When a large load F3 is applied from the outer balls 38 to an upper portion 35 d of the outer part of the outer ring 35 in the vehicle lateral direction, the upper portion 35 d is therefore likely to greatly deform radially outward as exaggeratingly shown by an imaginary line in FIG. 7.

As described above, the great deformation of the outer ring 35 adversely affects driving stability of the vehicle and a life of the bearing module 31.

FIG. 8A is a perspective view of an outer ring in JP 2011-94728 A. FIG. 8B is a front view of the outer ring in JP 2011-94728 A. As shown in FIGS. 8A and 8B, the outer ring 51 in JP 2011-94728 A is a modification of the conventional outer ring 35 shown in FIGS. 6 and 7. A plurality of ribs 51 b is formed on an outer periphery of an outer part of the outer ring 51 in the vehicle lateral direction at predetermined intervals in the circumferential direction. The ribs 51 b extend from the attachment flange 51 a toward the outer side in the vehicle lateral direction. Thus, in the outer part of the outer ring 51 in the vehicle lateral direction, regions where the ribs 51 b are formed have improved rigidity. However, parts 51 e between adjacent ribs 51 b have inadequate rigidity. This may not prevent the great deformation of the outer part of the outer ring 51 in the vehicle lateral direction.

SUMMARY OF THE INVENTION

An object of the invention is to provide a bearing module capable of suppressing deformation of both an outer part of an outer ring in a vehicle lateral direction and an inner part of the outer ring in the vehicle lateral direction.

A bearing module according to an aspect of the invention includes a knuckle having a hub unit supporting hole and a hub unit attached to the knuckle. The hub unit includes: an outer ring having on an outer periphery of the outer ring an attachment flange attached to the knuckle, and having an insertion portion fitted into the supporting hole, the insertion portion being a part of the outer ring, which is located on an inner side in a vehicle lateral direction with respect to the attachment flange; an inner shaft disposed on an inner periphery of the outer ring so as to be concentric with the outer ring and having an axial end portion to which a wheel is attached; and rolling elements in double rows that are disposed so as to be rollable between the outer ring and the inner shaft. An outer end face of the attachment flange in the vehicle lateral direction is located further outward in the vehicle lateral direction than a point of a load applied to the outer ring from the rolling elements located on an outer side in the vehicle lateral direction. A fitting surface for determining a radial position of the outer ring with respect to an inner periphery defining the supporting hole is formed on an outer periphery of the insertion portion. An inner edge of the fitting surface in the vehicle lateral direction is located further inward in the vehicle lateral direction than a point of a load applied to the outer ring from the rolling elements located on the inner side in the vehicle lateral direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a cross-sectional view showing a bearing module according to a first embodiment of the invention;

FIG. 2 is a partial enlarged view of FIG. 1;

FIG. 3 is a cross-sectional view showing a part of a bearing module according to a second embodiment of the invention;

FIG. 4 is a cross-sectional view showing a part of a bearing module according to a third embodiment of the invention;

FIG. 5 is a cross-sectional view showing a part of a bearing module according to a fourth embodiment of the invention;

FIG. 6 is a cross-sectional view showing a conventional bearing module;

FIG. 7 is a partial enlarged view of FIG. 6;

FIGS. 8A and 8B show a conventional outer ring, FIG. 8A is a perspective view showing the conventional outer ring, and FIG. 8B is a front view showing the conventional outer ring; and

FIG. 9 is a cross-sectional view showing a part of a conventional bearing module different from the conventional bearing module in FIG. 7.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a bearing module according to a first embodiment of the invention. As shown in FIG. 1, a bearing module 1 is a device for rotatably attaching a wheel serving as a driving wheel to a vehicle body of a vehicle such as an automobile. The bearing module 1 has a knuckle 3 extending from the vehicle body and a hub unit (wheel bearing device) 4. The hub unit 4 is attached to the knuckle 3. A wheel 2 and a brake rotor 22 that are wheel-side components are attached to the hub unit 4. In FIG. 1, a side on which the wheel is attached (the right side in FIG. 1) is an outer side in a vehicle lateral direction, and a center side of the vehicle body (the left side in FIG. 1) is an inner side in the vehicle lateral direction. In FIG, 1, an upper side of the figure is an upper side of the bearing module 1, and a lower side of the figure is a lower side of the bearing module 1.

The knuckle 3 forms a part of a suspension. A hub unit supporting hole 3 a is formed in a lower part of the knuckle 3 so as to extend in the right and left direction of the vehicle (the right and left direction in FIG. 1). FIG. 2 is a partial enlarged view of FIG. 1. As shown in FIG. 2, the hub unit 4 forms a double-row ball bearing. The hub unit 4 includes an outer ring (hub outer ring) 8, an inner shaft 9, balls (rolling elements) 10, 11 arranged in double rows, cages 12, 13, and seal members 14, 15. The outer ring 8 is fixed to the knuckle 3. The inner shaft 9 is disposed on an inner periphery of the outer ring 8 so as to be concentric with the outer ring 8. The balls 10, 11 arranged in double rows are disposed so as to be rollable between the outer ring 8 and the inner shaft 9. The cages 12, 13 retain the balls 10, 11 arranged in rows, respectively. The seal members 14, 15 seal the opposite ends of an annular clearance between the outer ring 8 and inner shaft 9.

The outer ring 8 is a fixed ring that is fixed to a vehicle body-side member. An outer-side outer ring raceway 8 a located on the outer side in the vehicle lateral direction and an inner-side outer ring raceway 8 b located on the inner side in the vehicle lateral direction are formed on the inner periphery of the outer ring 8 so as to be arranged along an axial direction. An attachment flange 8 c is formed on an outer periphery of the outer ring 8. An inner side face of the attachment flange 8 c in the vehicle lateral direction serves as a knuckle attachment surface 8 f. The knuckle attachment surface 8 f of the attachment flange 8 c is attached to an outer side face of the knuckle 3 in the vehicle lateral direction by attachment bolts 17. A part of the outer ring 8, which is located on the inner side in the vehicle lateral direction with respect to the attachment flange 8 c, serves as a cylindrical insertion portion 8 d. The insertion portion 8 d is inserted and fitted into the supporting hole 3 a of the knuckle 3. A substantially entire outer periphery of the insertion portion 8 d serves as a fitting surface 8 e fitted to a substantially entire inner periphery 3 a 1 defining the supporting hole 3 a.

In the first embodiment, the fitting surface 8 e means a region of the outer periphery of the insertion portion 8 d, which is press-fitted to the inner periphery 3 a 1 defining the supporting hole 3 a. When the insertion portion 8 d is inserted into the supporting hole 3 a, the fitting surface 8 e is press-fitted to the inner periphery 3 a 1 defining the supporting hole 3 a (fitted to the inner periphery 3 a 1 by interference fitting) such that a radial position of the outer ring 8 with respect to the inner periphery 3 a 1 is determined.

The inner shaft 9 has a cylindrical shape extending in the right and left direction of the vehicle. The inner shaft 9 serves as an axel, and the wheel 2 and the brake rotor 22 are attached to the inner shaft 9. The inner shaft 9 forms a rolling ring of the hub unit 4. The inner shaft 9 includes a cylindrical inner shaft body 19 and an annular inner ring member 20. The inner ring member 20 is press-fitted to an inner part of the inner shaft body 19 in the vehicle lateral direction. A flange portion 19 a is formed on an outer periphery of an outer end portion of the inner shaft body 19 in the vehicle lateral direction. Bolt holes 19 a 1 are formed on a periphery of the flange portion 19 a at prescribed intervals. The wheel 2 and the brake rotor 22 are attached to fixing bolts 21 that are press-fitted into the bolt holes 19 a 1. The wheel 2 and the brake rotor 22 are fastened together by nuts 24. An outer-side inner ring raceway 9 a that faces the outer-side outer ring raceway 8 a of the outer ring 8 is formed on an outer periphery of the inner shaft body 19. An inner-side inner ring raceway 9 b that faces the inner-side outer ring raceway 8 b of the outer ring 8 is formed on an outer periphery of the inner ring member 20. A shaft portion (not shown), which serves as a drive shaft, of a constant velocity joint coupled to a vehicle-side drive shaft is inserted into a center hole 19 b of the inner shaft body 19, and the shaft portion and the inner shaft 9 are connected to so as to be integrally rotatable.

The balls 10, 11 arranged in double rows are formed of the outer balls 10 located on the outer side in the vehicle lateral direction and the inner balls 11 located on the inner side in the vehicle lateral direction. The outer balls 10 are disposed so as to be rollable between the outer-side outer ring raceway 8 a of the outer ring 8 and the outer-side inner ring raceway 9 a of the inner shaft body 19. The inner balls 11 are disposed so as to be rollable between the inner-side outer ring raceway 8 b of the outer ring 8 and the inner-side inner ring raceway 9 b of the inner ring member 20.

An outer end face 8c1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than a point P1 of the load applied from the outer balls 10 to the outer ring 8. The point P1 of the load is a contact point between the outer ball 10 and the outer-side outer ring raceway 8 a. The knuckle attachment surface 8 f of the attachment flange 8 c is located further inward in the vehicle lateral direction than the point P1 of the load. An inner edge 8 e 1 of the fitting surface 8 e in the vehicle lateral direction is located further inward in the vehicle lateral direction than a point P2 of the load applied from the inner balls 11 to the outer ring 8. The point P2 of the load is a contact point between the inner ball 11 and the inner-side outer ring raceway 8 b.

According to the first embodiment, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied from the outer balls 10 to the outer ring 8, and the attachment flange 8 c is disposed at a position outward in the vehicle lateral direction in the outer ring 8. Providing the attachment flange 8 c can therefore increase the rigidity of the outer part of the outer ring 8 in the vehicle lateral direction. In the outer ring 51 described in JP 2011-94728 A, which is shown in FIG. 8, the parts 51 c between adjacent ribs 5 lb have inadequate rigidity. On the other hand, in the first embodiment, because the attachment flange 8 c is formed over the entire outer periphery of the outer part of the outer ring 8 in the vehicle lateral direction, the entire periphery of the outer part of the outer ring 8 in the vehicle lateral direction can have sufficiently high rigidity.

Even if a large load F1 is applied from the outer balls 10 to an upper portion 8 g of the outer part of the outer ring 8 in the vehicle lateral direction through the point P1 of the load during cornering of the vehicle, etc., the radially outward deformation of the upper portion 8 g can therefore be suppressed. The upper portion 8 g means a portion of the outer part of the outer ring 8 in the vehicle lateral direction, which is located on the upper side with respect to a central axis of the outer ring 8. According to the first embodiment, because the attachment flange 8 c is disposed at a position outward in the vehicle lateral direction in the outer ring 8, an inner part of the outer ring 8 in the vehicle lateral direction has low rigidity. When a large load F2 is applied from the inner balls 11 to an upper portion 8 d 1 of the insertion portion 8 d through the contact point P2 during cornering of the vehicle, etc., an inner end portion of the upper portion 8 d 1 in the vehicle lateral direction may therefore deform radially outward. The upper portion 8 d 1 means a portion of the insertion portion 8 d, which is located on the upper side with respect to a central axis of the insertion portion 8 d.

According to the first embodiment, however, the fitting surface 8 e of the insertion portion 8 d is press-fitted into the supporting hole 3 a such that there is no clearance between the fitting surface 8 e and the inner periphery 3 a 1 defining the supporting hole 3 a. Even if the large load F2 is applied to the upper portion 8 d 1 of the insertion portion 8 d, the knuckle 3 can therefore reliably receive the load F2 through the fitting surface 8 e and the inner periphery 3 a 1. This can suppress the radially outward large deformation of the upper portion 8 d 1 of the insertion portion 8 d. The substantially entire outer periphery of the insertion portion 8 d serves as the fitting surface 8 e fitted to the substantially entire inner periphery 3 a 1 defining the supporting hole 3 a. An axial length L1 of the fitting surface 8 c in the first embodiment can therefore be increased compared to an axial length of a fitting surface in the case where a part of an outer periphery of an insertion portion serves as a fitting surface, and a contact area between the fitting surface 8 e and the inner periphery 3 a 1 can thus be increased. A contact surface pressure between the fitting surface 8 e and the inner periphery 3 a 1 can be thus reduced compared to a contact surface pressure between a fitting surface and an inner periphery in the case where a part of an outer periphery of an insertion portion serves as a fitting surface. This prevents an excessive force from being applied to the knuckle 3 when the large load F2 is applied to the upper portion 8 d 1 of the insertion portion 8 d.

In addition, because there is no clearance between the fitting surface 8 e of the insertion portion 8 d and the inner periphery 3 a 1 defining the supporting hole 3 a, a member for filling a clearance is not required. This can reduce the number of components and thus achieve a reduction in cost. In order to install a member for filling a clearance, the outer periphery of the insertion portion 8 d, the inner periphery 3 a 1, etc. are not required to be processed. In addition, because the insertion portion 8 d of the outer ring 8 is press-fitted into the supporting hole 3 a of the knuckle 3, a fixing force for fixing the outer ring 8 to the knuckle 3 is generated by this press-fitting. This can reduce the number of attachment bolts 17 for fixing the outer ring 8 to the knuckle 3. Compared to a conventional case where the number of attachment bolts 17 is four, for example, the number of attachment bolts 17 can be reduced to two or three.

Furthermore, the insertion portion 8 d of the outer ring 8 is press-fitted into the supporting hole 3 a of the knuckle 3 such that there is no clearance between the fitting surface 8 e of the insertion portion 8 d and the inner periphery 3 a 1 defining the supporting hole 3 a. This can improve the rigidity of the hub unit 4 forming a double-row ball bearing.

FIG. 3 is a cross-sectional view showing a second embodiment of the invention. This embodiment is a modification of the first embodiment shown in FIGS. 1 and 2. In this embodiment, as shown in FIG. 3, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied from the outer balls 10 to the outer ring 8. In a fitting surface 8 e of the insertion portion 8 d, only an inner region of the fitting surface 8 e in the vehicle lateral direction serves as a press-fitting surface 8 e 2 press-fitted into the supporting hole 3 a of the knuckle 3. An outer edge 8 e 4 of the press-fitting surface 8 e 2 in the vehicle lateral direction is located, for example, at a position same as or close to a center 11 a of the inner ball 11 in an axial direction. A region of the fitting surface 8 e, which is located on the outer side in the vehicle lateral direction with respect to the press-fitting surface 8 e 2, serves as a non-press-fitting surface 8 e 3 that is not press-fitted into the supporting hole 3 a. The non-press-fitting surface 8 e 3 faces the inner periphery 3 a 1 defining the supporting hole 3 a with an annular clearance 23 that is extremely small (in a radial direction) interposed therebetween. In the following description, the extremely small clearance 23 will be referred to as a fitting clearance. The fitting clearance 23 is, for example, around 0.06 mm. In the second embodiment, the fitting surface 8 e means two regions in the outer periphery of the insertion portion 8 d, that is, a region that is press-fitted to the inner periphery 3 a 1 defining the supporting hole 3 a and a region that faces the inner periphery 3 a 1 with the fitting clearance 23 interposed therebetween. When the insertion portion 8 d is inserted into the supporting hole 3 a, the press-fitting surface 8 e 2 is press-fitted to the inner periphery 3 a 1 defining the supporting hole 3 a such that a radial position of the outer ring 8 with respect to the inner periphery 3 a 1 is determined.

In the second embodiment, as in the first embodiment, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied from the outer balls 10 to the outer ring 8. Accordingly, providing the attachment flange 8 c can increase the rigidity of the outer part of the outer ring 8 in the vehicle lateral direction. Even if the large load F1 is applied from the outer balls 10 to the upper portion 8 g of the outer part of the outer ring 8 in the vehicle lateral direction through the point P1 of the load during cornering of the vehicle, etc., the radially outward deformation of the upper portion 8 g can therefore be suppressed. The upper portion 8 g means a portion of the outer part of the outer ring 8 in the vehicle lateral direction, which is located on the upper side with respect to a central axis of the outer ring 8. In addition, the press-fitting surface 8 e 2 of the fitting surface 8 e of the insertion portion 8 d is press-fitted into the supporting hole 3 a such that there is no clearance between the press-fitting surface 8 e 2 and the inner periphery 3 a 1 defining the supporting hole 3 a. Even if the large load F2 is applied to the upper portion 8 d 1 of the insertion portion 8 d, the knuckle 3 can therefore reliably receive the load F2 through the press-fitting surface 8 e 2 and the inner periphery 3 a 1. This can suppress the radially outward large deformation of the upper portion 8 d 1 of the insertion portion 8 d. The upper portion 8 d 1 means a portion of the insertion portion 8 d, which is located on the upper side with respect to a central axis of the insertion portion 8 d.

Furthermore, only an inner region of the fitting surface 8 e in the vehicle lateral direction serves as the press-fitting surface 8 e 2 and is press-fitted into the supporting hole 3 a of the knuckle 3. This can prevent an excessive fixing force generated by press-fitting from being applied from the outer ring 8 to the knuckle 3. The insertion portion 8 d can therefore be easily removed from the supporting hole 3 a at the time of maintenance of the bearing module 1. In addition, a large force for press-fitting the insertion portion 8 d into the supporting hole 3 a is not required at the time of assembly of the bearing module 1, and the press-fitting operation can be thus easily performed.

FIG. 4 is a cross-sectional view showing a third embodiment of the invention. In this embodiment, as shown in FIG. 4, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied from the outer balls 10 to the outer ring 8. A fitting clearance 23 is formed between an entire fitting surface 8 e and the inner periphery 3 a 1 defining the supporting hole 3 a so as to extend along an entire axial length of the fitting surface 8 e. The inner edge 8 e 1 of the fitting surface 8 e in the vehicle lateral direction is located further inward in the vehicle lateral direction than the point P2 of the load applied from the inner balls 11 to the outer ring 8. An axial length of the fitting surface 8 e is L2. In the third embodiment, the fitting surface 8 e means a region of the outer periphery of the insertion portion 8 d, which faces the inner periphery 3 a 1 defining the supporting hole 3 a with the fitting clearance 23 interposed therebetween. When the insertion portion 8 d is inserted into the supporting hole 3 a, the fitting surface 8 e is brought into contact with the inner periphery 3 a 1 defining the supporting hole 3 a or is guided by the inner periphery 3 a 1 such that a radial position of the outer ring 8 with respect to the inner periphery 3 a 1 is determined. Even with the insertion portion 8 d fitted into the supporting hole 3 a, a radial position of the outer ring 8 with respect to the inner periphery 3 a 1 defining the supporting hole 3 a can be determined by the fitting surface 8 e.

In the third embodiment, as in the first embodiment, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied from the outer balls 10 to the outer ring 8. Accordingly, providing the attachment flange 8 c can increase the rigidity of the outer part of the outer ring 8 in the vehicle lateral direction. Even if the large load F1 is applied from the outer balls 10 to the upper portion 8 g of the outer part of the outer ring 8 in the vehicle lateral direction through the point P1 of the load during cornering of the vehicle, etc., the radially outward deformation of the upper portion 8 g can therefore be suppressed. The upper portion 8 g means a portion of the outer part of the outer ring 8 in the vehicle lateral direction, which is located on the upper side with respect to a central axis of the outer ring 8. In addition, forming the fitting clearance 23 can facilitate insertion and fitting of the insertion portion 8 d into the supporting hole 3 a at the time of assembly of the bearing module 1 and also facilitate removal of the insertion portion 8 d from the supporting hole 3 a at the time of maintenance of the bearing module 1. When the insertion portion 8 d is inserted into the supporting hole 3 a, a jig for assisting this insertion may be used. In the case where the fitting clearance 23 is formed between the entire fitting surface 8 e and the inner periphery 3 a 1 defining the supporting hole 3 a, and the large load F2 is applied from the inner balls 11 to the upper portion 8 d 1 of the insertion portion 8 d, the upper portion 8 d 1 may largely deform radially outward. It will be described next that such large deformation does not occur in the third embodiment, compared to the conventional bearing module. The upper portion 8 d 1 means a portion of the insertion portion 8 d, which is located on the upper side with respect to a central axis of the insertion portion 8 d.

FIG. 9 is a cross-sectional view showing a part of a conventional bearing module different from the conventional bearing module in FIG. 7. In a conventional bearing module 31 shown in FIG. 9, as in the third embodiment, an attachment flange 35 a is formed at a position outward in the vehicle lateral direction in an outer periphery of an outer ring 35. In an outer periphery of an insertion portion 35 b of the outer ring 35, only an outer region of the outer periphery in the vehicle lateral direction serves as a fitting surface 35 e that faces an outer region of an inner periphery 32 a 1 defining a supporting hole 32 a in the vehicle lateral direction with a fitting clearance 41 whose radial length is extremely small interposed therebetween. In the description of this conventional example, the fitting surface 35 e means a region of the outer periphery of the insertion portion 35 b, which faces the inner periphery 32 a 1 defining the supporting hole 32 a with the fitting clearance 41 interposed therebetween. An inner edge 35 e 1 of the fitting surface 35 e in the vehicle lateral direction is located further outward in the vehicle lateral direction than a point P4 of the load applied from the inner balls 39 to the outer ring 35.

A region of the outer periphery of the insertion portion 35 b, which is located on the inner side in the vehicle lateral direction with respect to the fitting surface 35 e, serves as a non-fitting surface 35 f that faces the inner periphery 32 a 1 defining the supporting hole 32 a with an annular clearance 42 larger than the fitting clearance 41 interposed therebetween. The non-fitting surface 35 f means a region of the outer periphery of the insertion portion 35 b, which faces the inner periphery 32 a 1 defining the supporting hole 32 a with the annular clearance 42 larger than the fitting clearance 41 interposed therebetween. With the insertion portion 35 b fitted into the supporting hole 32 a, the non-fitting surface 35 f therefore has no function of determining a radial position of the outer ring 35 with respect to the inner periphery 32 a 1 defining the supporting hole 32 a.

According to the conventional configuration shown in FIG. 9, in the outer periphery of the insertion portion 35 b, only the outer region of the outer periphery in the vehicle lateral direction serves as the fitting surface 35 e, and the inner edge 35 e 1 of the fitting surface 35 e in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P4 of the load applied from the inner balls 39 to the outer ring 35. In the conventional configuration shown in FIG. 9, as exaggeratingly shown by an imaginary line in FIG. 9, an outer periphery of an upper portion 35 b 1 is therefore brought into contact with the inner periphery 32 a 1 defining the supporting hole 32 a by largely deforming radially outward the upper portion 35 b 1 of the insertion portion 35 b. In other words, the radially outward large deformation of the upper portion 35 b 1 is permitted. The upper portion 35 b 1 means a portion of the insertion portion 35 b, which is located on the upper side with respect to a central axis of the insertion portion 35 b. When the large load F4 is applied from the inner balls 39 to the upper portion 35 b 1 of the insertion portion 35 b during cornering of the vehicle, etc., the upper portion 35 b 1 may therefore largely deform radially outward. In addition, a deformation angle θ1 between a position of the upper portion 35 b 1 before deformation shown by a continuous line and a position of the upper portion 35 b 1 after deformation shown in by an imaginary line is increased.

On the other hand, in the third embodiment, the substantially entire outer periphery of the insertion portion 8 d serves as the fitting surface 8 e, the fitting surface 8 e faces the substantially entire inner periphery 3 a 1 defining the supporting hole 3 a, and the inner edge 8 e 1 of the fitting surface 8 e in the vehicle lateral direction is located further inward in the vehicle lateral direction than the point P2 of the load applied from the inner balls 11 to the outer ring 8. Accordingly, as shown by an imaginary line in FIG. 4, the outer periphery (the fitting surface 8 e) of the upper portion 8 d 1 is brought into contact with the inner periphery 3 a 1 defining the supporting hole 3 a without largely deforming radially outward the upper portion 8 d 1 of the insertion portion 8 d.

In other words, the radially outward large deformation of the upper portion 8 d 1 of the insertion portion 8 d is suppressed. Even if the large load F2 is applied from the inner balls 11 to the upper portion 8 d 1 of the insertion portion 8 d during cornering of the vehicle, etc., the radially outward large deformation of the upper portion 8 d 1 can therefore be suppressed. Even if the upper portion 8 d 1 deforms, a deformation angle θ (see FIG. 4) between a position of the upper portion 8 d 1 before deformation shown by a continuous line and a position of the upper portion 8 d 1 after deformation shown by the imaginary line is smaller than the conventional deformation angle θ1 shown in FIG. 9. In the conventional configuration shown in FIG. 9, an axial length L3 of the fitting surface 35 e is shorter than the axial length L2 of the fitting surface 8 e in this embodiment, and an axial length L4 of the non-fitting surface 35 f is longer than the axial length L3 of the fitting surface 35 e.

FIG. 5 is a cross-sectional view showing a fourth embodiment of the invention. This embodiment is a modification of the third embodiment shown in FIG. 4. In this embodiment, as shown in FIG. 5, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied from the outer balls 10 to the outer ring 8. Only an inner region of the outer periphery of the insertion portion 8 d in the vehicle lateral direction serves as the fitting surface 8 e that faces the inner periphery 3 a 1 defining the supporting hole 3 a with an annular fitting clearance 23 (extending in the radial direction) interposed therebetween. The inner edge 8 e 1 of the fitting surface 8 e in the vehicle lateral direction is located further inward in the vehicle lateral direction than the point P2 of the load applied from the inner balls 11 to the outer ring 8. An outer edge 8 e 5 of the fitting surface 8 e in the vehicle lateral direction is located, for example, at a position same as or close to the center 11 a of the inner ball 11 in an axial direction. In the fourth embodiment, the fitting surface 8 e means a region of the outer periphery of the insertion portion 8 d, which faces the inner periphery 3 a 1 defining the supporting hole 3 a with the fitting clearance 23 interposed therebetween. When the insertion portion 8 d is inserted into the supporting hole 3 a, the fitting surface 8 e is brought into contact with the inner periphery 3 a 1 defining the supporting hole 3 a or is guided by the inner periphery 3 a 1 such that a radial position of the outer ring 8 with respect to the inner periphery 3 a 1 is determined. Even with the insertion portion 8 d fitted into the supporting hole 3 a, the radial position of the outer ring 8 with respect to the inner periphery 3 a 1 defining the supporting hole 3 a is determined by the fitting surface 8 e. A region of the outer periphery of the insertion portion 8 d, which is located on the outer side in the vehicle lateral direction with respect to the fitting surface 8 e, serves as a non-fitting surface 8 h that faces the inner periphery 3 a 1 defining the supporting hole 3 a with an annular clearance 25 larger than the fitting clearance 23 interposed therebetween. In the fourth embodiment, the non-fitting surface 8 h means a region of the outer periphery of the insertion portion 8 d, which faces the inner periphery 3 a 1 defining the supporting hole 3 a with the annular clearance 25 larger than the fitting clearance 23 interposed therebetween. With the insertion portion 8 d fitted into the supporting hole 3 a, the non-fitting surface 8 h therefore has no function of determining the radial position of the outer ring 8 with respect to the inner periphery 3 a 1 defining the supporting hole 3 a.

In the fourth embodiment, as in the third embodiment, the outer end face 8 c 1 of the attachment flange 8 c in the vehicle lateral direction is located further outward in the vehicle lateral direction than the point P1 of the load applied to from the outer balls 10 to the outer ring 8. Accordingly, providing the attachment flange 8 c can increase the rigidity of the outer part of the outer ring 8 in the vehicle lateral direction. Even if the large load Fl is applied from the outer balls 10 to the upper portion 8 g of the outer part of the outer ring 8 in the vehicle lateral direction through the point P1 of the load during cornering of the vehicle, etc., the radially outward deformation of the upper portion 8 g can therefore be suppressed. The upper portion 8 g means a portion of the outer part of the outer ring 8 in the vehicle lateral direction, which is located on the upper side with respect to a central axis of the outer ring 8.

In addition, the inner region of the outer periphery of the insertion portion 8 d in the vehicle lateral direction serves as the fitting surface 8 e and the fitting surface 8 e faces the region of the inner periphery 3 a 1 defining the supporting hole 3 a, which is located on the inner side in the vehicle lateral direction. The inner edge 8 e 1 of the fitting surface 8 e in the vehicle lateral direction is located further inward in the vehicle lateral direction than the point P2 of the load applied from the inner balls 11 to the outer ring 8. Accordingly, the outer periphery (the fitting surface 8 e) of the upper portion 8 d 1 is brought into contact with the inner periphery 3 a 1 defining the supporting hole 3 a without largely deforming radially outward the upper portion 8 d 1 of the insertion portion 8 d. In other words, the radially outward large deformation of the upper portion 8 d 1 of the insertion portion 8 d is suppressed. The upper portion 8 d 1 means a portion of the insertion portion 8 d, which is located on the upper side with respect to a central axis of the insertion portion 8 d. Even if the large load F2 is applied from the inner balls 11 to the upper portion 8 d 1 of the insertion portion 8 d during cornering of the vehicle, etc., the radially outward large deformation of the upper portion 8 d 1 can therefore be suppressed.

Furthermore, forming the fitting clearance 23 and the annular clearance 25 can facilitate insertion and fitting of the insertion portion 8 d into the supporting hole 3 a at the time of assembly of the bearing module 1 and also facilitate removal of the insertion portion 8 d from the supporting hole 3 a at the time of maintenance of the bearing module 1. In addition, the fitting surface 8 e is formed by machining the outer periphery of the insertion portion 8 d. An axial length of the fitting surface 8 e in the fourth embodiment is smaller than an axis length of the fitting surface 8 e in the third embodiment. The fitting surface 8 e in the fourth embodiment can therefore be easily formed compared to the fitting surface 8 e in the third embodiment.

In the above embodiments, a ball is used as a rolling element, and however, a tapered roller may be used as a rolling element.

According to a bearing module of the invention, deformation of both an outer part of an outer ring in the vehicle lateral direction and an inner part of an outer ring in the vehicle lateral direction can be suppressed. 

What is claimed is:
 1. A bearing module comprising: a knuckle having a hub unit supporting hole; and a hub unit attached to the knuckle, the hub unit including an outer ring having on an outer periphery of the outer ring an attachment flange attached to the knuckle, and having an insertion portion fitted into the supporting hole, the insertion portion being a part of the outer ring, which is located in an inner side in a vehicle lateral direction with respect to the attachment flange, an inner shaft disposed on an inner periphery of the outer ring so as to be concentric with the outer ring and having an axial end portion to which a wheel is attached, and rolling elements in double rows that are disposed so as to be rollable between the outer ring and the inner shaft, wherein an outer end face of the attachment flange in the vehicle lateral direction is located further outward in the vehicle lateral direction than a point of a load applied to the outer ring from the rolling elements located on an outer side in the vehicle lateral direction, a fitting surface for determining a radial position of the outer ring with respect to an inner periphery defining the supporting hole is formed on an outer periphery of the insertion portion, and an inner edge of the fitting surface in the vehicle lateral direction is located further inward in the vehicle lateral direction than a point of a load applied to the outer ring from the rolling elements located on the inner side in the vehicle lateral direction.
 2. The bearing module according to claim 1, wherein the fitting surface of the insertion portion is press-fitted into the supporting hole.
 3. The bearing module according to claim 1, wherein a fitting clearance is formed between the fitting surface and the inner periphery defining the supporting hole. 